This invention relates to an axle assembly having multiple wheels at each end of an axle in which one wheel is permitted to rotate relative to the other wheel, and more specifically, the invention relates to a differential interconnecting the wheels for heavy duty vehicles requiring a gear reduction assembly.
Axle assemblies having dual wheels on either end of the axle have been used to increase the load bearing capability of heavy duty vehicles. Typically the pair of wheels on each end of the axle assembly is secured together so that they rotate together about an axis. Some heavy duty vehicles, such as lift trucks, undergo numerous turning maneuvers which wear the tires significantly. The tire wear is caused when the tires scrub, or drag, since the wheels that are secured together must travel different distances at the inside and outside of the turning radius. Tire wear and maintenance on heavy duty lift trucks due to scrub cost thousands of dollars annually per vehicle.
Dual wheel assembly designs have been proposed that permit the wheels to rotate relative to one another to reduce scrubbing during vehicle turns while driving at least one of the wheels to propel the vehicle. Certain driving conditions require that both wheels be driven to provide enough traction to propel the vehicle and its load. Some designs have been developed which utilize a differential gear set between the wheels so that both wheels may be driven at the same rate when the vehicle travels a straight path. The differential permits the wheels to rotate relative to one another when the vehicle travels a curved path to reduce scrubbing. Heavy duty vehicles, such as lift trucks, typically require a gear reduction assembly, or final drive, between the drive axle and each drive wheel to produce sufficient torque to propel the vehicle and its load. However, the prior art does not address the need of developing a differential assembly for use with a final drive. Therefore, what is needed is a dual wheel assembly that incorporates a differential with a final drive for maintaining desire traction and torque multiplication while reducing tire scrub.